Ability to edit MapTile-Provider


#1

Would be great to add/edit Map-Tile Providers. (as of now, currently hardcoded in https://github.com/getredash/redash/blob/master/client/app/visualizations/map/index.js)

This way one could even add things like API-Key (like with thunderforest now (https://www.thunderforest.com/docs/apikeys/)) to the URL, plus add even other self-customized tiles.